1. Field of the Invention
The present invention relates generally to an anti-backflow device, and more particularly to an anti-backflow device for used in a fan unit so as to prevent occurrence of air backflow into the fan unit upon activation thereof.
2. The Prior Arts
Rapid advance of science technology results in ceaseless development of electronic products. The functions thereof are still rising as days go by so do the features, but the manufacturing cost is forced to reduce nevertheless. Therefore, only high efficient function or design with low manufacturing cost is a trend for the manufactures to follow in order to satisfy the demand of the majority of the consumers.
The more the functions and features an electronic product possesses, the more the heat is generated by several components of the electronic product. The generated heat may cause damage more or less to the entire system installed in the electronic product, thereby resulting in malfunction of the electronic product. A major research for all the manufactures of electronic devices is how to dissipate the generated heat effectively with little cost and with little expense. Presently, a fan unit is provided in a majority of the electronic devices in order to dissipate the generated heat upon operation of the electronic devices.
FIG. 1 shows a conventional fan unit installed in an electronic device, such as a PC (Personal Computer) or a server system, which is used to dissipate out the generated heat therein upon activation of the fan unit. The conventional fan unit includes a frame body (b) and a fan (a) mounted rotatably in the frame body (b) so as to create an air flow upon activation of the fan unit so that the generated heat in an interior of the electronic device is dissipated to an exterior of the electronic device with the air flow. One drawback resulted from the use of the fan unit resides in that an air backflow is generated in case the fan unit malfunctions or is deactivated. To be more specific, the backflow is an unwanted reverse flow. The backflow is generally occurred and more aggravated in those devices or systems which have cross connection of fluid supplies, like plumbing fixtures or piping systems. The air backflow into the product sometimes causes the operating system unstable. In order to eliminate this drawback, some manufacturers have installed anti-backflow devices, like shutter types, in most of the devices so as to prevent the occurrence of unwanted reverse flow, simply “backflow”.